The overarching goals of this program of research are: 1) to understand what factors contribute to physiologic stress in young children, 2) to examine the consequences of physiologic stress on child health, and 3) to determine what interventions would mitigate excessive physiologic stress. We focus on the hypothalamic-pituitary-adrenal (HPA) axis, a neuroendocrine system producing cortisol in humans. According to several models, frequent and/or excessive activation of the HPA-axis contributes to increased risk for poor physical and psychological health. In previous work, full-day child care has been associated with rising cortisol levels across the day at child care, but the more normative falling pattern for these same children across the day at home. The effect has been robust and replicable; however several important questions remain unanswered. The proposed project will utilize an ecological systems approach to address three important factors that may contribute to elevated cortisol or disturbed cortisol rhythms in young children: 1) whether the long hours of full-day child care are producing the cortisol elevations and therefore whether children in half-day programs would be protected, 2) whether the family context, particularly family strain and maternal depression put children at increased risk for rising cortisol at home and at child care, and 3) whether child care and family factors have additive or interaction effects on cortisol patterning at child care. The proposed study will examine the effects of child care and family factors on salivary cortisol patterning in two samples of children; those utilizing Head Start (n=60), and those utilizing non-university affiliated child care centers (n=60). Extensive efforts will be made to recruit previously underrepresented families, including African-American and Hispanic families. Relevance: The proposed project is directly relevant to the health of children as it assesses a rising pattern of the potent stress-sensitive hormone cortisol across the child care day. Elevated cortisol and a disturbed diurnal rhythm are indicators of physiologic stress and are risk factors for infection, cardiovascular disease, and emotional disorders. Understanding the factors that contribute to rising cortisol will allow targeted intervention efforts. [unreadable] [unreadable] [unreadable]